The present invention relates to a fuel cell system and, more particularly, a reformed fuel fuel cell system to produce electricity. Reformed fuel fuel cell systems typically use one of three types of fuel processors, namely, a catalytic steam reformer, an auto-thermal reformer, or catalytic partial oxidizer as are commonly known in the art.
Fuel cell power plants for producing electricity are well known in the art. U.S. Pat. No. 3,976,507 discloses a pressurized fuel cell power plant which operates at a pressure greater than ambient pressure. While the power plant disclosed in U.S. Pat. No. 3,976,507 is effective and useful for generating electricity, the fact that the plant operates under pressure does not render it particularly useable for a reformed fuel fuel cell system with vehicular applications. In a low pressure reformed fuel fuel cell system, the size of the system and the pressure drop experienced during operation of the system are critical factors in producing an effective, compact system which is useable in vehicular applications.
Naturally, it would be highly desirable to produce a reformed fuel fuel cell system which can operate effectively at ambient pressure while maintaining a compact size which is suitable for use in the system. In order to achieve the foregoing, each component in the reformed fuel fuel cell system must be designed in a manner which takes into consideration the allowable pressure drop which may occur within the system and the sized limitation constraints necessary to make such a system practical. Therefore, any savings in size and pressure drop which can be obtained with any of the system components is highly desirable. Accordingly, it is a principal object of the present invention to provide a compact precooler which is useful in a reformed fuel fuel cell system.
It is a particular object of the present invention to provide a compact precooler which is effective in reducing the temperature of a fuel processor exit gas stream while ensuring minimal pressure drop.
It is a still further object of the present invention to provide a compact precooler between a fuel processor and shift converter which provides sufficient residence time to effectively cool the reformer exit gas stream to a desired temperature and evaporate all water used in the precooler.
It is a still further object of the present invention to provide a process for cooling a fuel processor exit gas stream in an effective manner while limiting pressure drop.
Further objects and advantages of the present invention will appear hereinbelow.
The foregoing objects and advantages are obtained by way of the present invention by providing, in a near ambient pressure operated reformed fuel fuel gas system, a precooler between the fuel processor and shift converter. The precooler includes an atomizing water inlet, an inlet for the reformed gas and a packing of high surface area material which increases the vaporizing surface for the water in the precooler so as to effectively cool the hot reformed gas in a more compact unit.
The present invention is further drawn to a process for cooling a reformed exit gas from a fuel processor operated at near ambient pressure so as to ensure a cooled reformed gas at the desired temperature wherein the gas stream is substantially free of water droplets. By vaporizing all the water in the precooler, the process ensures a minimal pressure drop from the inlet of the precooler to the outlet of the precooler.
Further features and advantages of the present invention will be more fully apparent in light of the following detailed description of the preferred embodiment of the present invention as illustrated in the accompanying drawings wherein:
FIG. 1 is a schematic representation of an auto-thermal reformer fuel cell system employing the precooler of the present invention.
FIG. 2 is a cross sectional view through the precooler in accordance with the present invention.